Remove busy looping during watchdog reset.
Each polling of W_PEND_WTGR bit ("finish posted
write") after watchdog reset takes 120-140us
on BeagleBone Black board. Current U-Boot code
has watchdog resets in random places and often
there is situation when watchdog is reset
few times in a row in nested functions.
This adds extra delays and slows the whole system.
Instead of polling W_PEND_WTGR bit, we skip
watchdog reset if the bit is set. Anyway, watchdog
is in the middle of reset *right now*, so we can
just return.
This noticeably increases performance of the
system. Below are some measurements on BBB:
- DFU upload over USB 15% faster
- fastboot image upload 3x times faster
- USB ep0 transfers with 4k packets 20% faster
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Tested-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Tested-by: Alex Kiernan <alex.kiernan@gmail.com>
The OMAP WDT IP block requires to be stopped before any write to its
registers is performed.
This problem has been thoroughly described in Linux kernel:
"watchdog: omap: assert the counter being stopped before reprogramming:
SHA1: 530c11d432727c697629ad5f9d00ee8e2864d453
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
Ruslan Bilovol
Lukasz Majewski
Heiko Schocher